Yemeni authorities say apparent U.S. drone strikes on al-Qaida's branch in Yemen have intensified, with confirmation of a fourth deadly missile attack on the group in the past week.

Authorities said the latest strike happened late Saturday, when an unmanned aircraft killed three suspected al-Qaida members riding a vehicle in the central province of Bayda. Officials said one of the dead was a senior al-Qaida operative, Saleh Mohammed al-Ameri.

In the earlier drone strikes, two al-Qaida insurgents were killed in the eastern province of Hadramawt on Friday, while at least six others were killed in separate missile attacks on December 24.

U.S.-backed Yemeni government forces have been fighting al-Qaida militants in the country for years. Authorities have reported dozens of apparent U.S. drone strikes in 2012, but the staging of four such attacks in one week is unusual.